docs: def delete_expired_users(self):
          """
          Checks for expired users and delete's the ``User`` associated with
          it. Skips if the user ``is_staff``.
  
          :return: A list containing the deleted users.
  
          """
          deleted_users = []
          for user in get_user_model().objects.filter(is_staff=False,
                                                      is_active=False):
              if user.userena_signup.activation_key_expired():
                  deleted_users.append(user)
                  user.delete()
          return deleted_users